(1) Field of the Invention
The present invention relates to a water-in-oil (hereinafter, abbreviated as W/O) emulsion explosive composition containing an inorganic chlorate as a sensitizer and having excellent storage stability, low-temperature detonability and explosion reactivity.
(2) Description of the Prior Art
Conventional water-gel explosive consists mainly of an oxidizer, a reducing agent (fuel), a crosslinking agent, a sensitizer and foams. In the water-gel explosive, as the sensitizer, there have been used monomethylamine nitrate, ethylene glycol mononitrate, aluminum powder and the like; and as the oxidizer, there have been used very stable inorganic nitrate or inorganic perchlorate alone or in admixture in order to ensure the storage stability of the water-gel explosive. Further, the use of inorganic chlorate as the other oxidizer is disclosed in U.S. Patent application Ser. Nos. 3,282,753, 3,715,247 and 3,985,593. However, inorganic chlorate is very inferior in stability to the above described oxidizers, and decomposes in a very short period of time in the water-gel explosive. In order to obviate this drawback, the above described U.S. patent applications describe that it is desirable to add alkali substances, such as sodium carbonate, potassium hydroxide and the like, to the water-gel explosive in order to improve the stability during the storage of the explosive. However, the use of alkali substances in the adjustment of the pH of conventional water-gel explosive deteriorates ammonium nitrate used as a main oxidizer and hinders the development of the crosslinking ability of crosslinking agent which serves to form the water-gel explosive.
The inventors have considered that one of the causes of decomposition of inorganic chlorate in a water-gel explosive is its crystallization in an aqueous solution of ammonium nitrate, and have made various investigations in order to prevent the crystallization of inorganic chlorate. As a result, the inventors have found out that, when a W/O emulsion explosive is produced, the droplets which form the disperse phase of the emulsion and contains inorganic chlorate dissolved therein, are formed into a very small size. Therefore, the crystallization of the inorganic chlorate is suppressed and the inorganic chlorate is prevented from being decomposed, and the W/O emulsion explosive has very high low-temperature detonability and explosion reactivity due to the action of the inorganic chlorate. As a result, the present invention has been accomplished.